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The Cropwalker - Volume 4 Issue 25

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Crop Conditions

Weather Timely rains fell across most of western and central Ontario last week. This resulted in water logged soils in some areas and lodged wheat in many areas. Wheat earliest in Essex/Kent may be ready to harvest by the weekend. In that area very little lodging because wheat was far enough advanced. In other areas of western Ontario, a noticeable amount of lodging. Overall, the yield loss due to lodging should be more than offset by the yield gained by timely rains. In some of these fields the wheat heads are about 6-8” off the ground. This bodes well. General consensus is that about 10-20% of wheat fields in some areas have some lodging.  Corn is really doing well. The dry period in early June forced roots to go deeper. Rains now bodes well for yield. Not much to do now except watch for diseases, insects and plan for next year. Soybeans last rains meant that any viable beans sitting in dry soil are now establishing. Most fields are at R1 (begin flowering) or will be this week.  Bean leaf beetle first generation feeding was at a low level earlier. Aphids are building in some fields. Threshold is 250 per plant and building. Expect to see some spots with aphids as well as spider mites along outside of fields where grasses have been cut or have dried out. If found early, spraying the outside of the field should control them, once past the headland, you will have to spray the whole field. White mould may be an issue in fields where it traditionally has been bad. (See last week’s Cropwalker for product strategy by the various companies) Forages earlier I felt we would have a shortage but recent rains are quickly dispelling that for most Ontario farmers. Some parts are still facing possible forage shortages with weak 2nd cut volumes in parts of western Ontario second is well underway with great yields. One reader feels they will have at least 4.0 tons of dry matter between their first 2 cuts and looking at another 3 tons from the next 2 cuts. Alfalfa weevil adults can be a problem in new seedings in fields adjacent to fields where they were heavy, in first cut. The larva pupates and emerge as adults very shortly. These adults will feed for awhile and then burrow into the ground to overwinter. If there is no alfalfa to feed on when they emerge now, they will fly to the nearest field which sometimes is new seeding.


Things to Do This Week (There are a lot)

1.     Decide white mould strategy. What products, what rates and what fields.

2.     Final inspection of grain bins and wagons/trucks for on farm wheat storage, do not use wagons designated for treated seed for grain harvest.

3.     Check winter wheat fields for preharvest weed control. This may be because you missed in-crop herbicide, or there are perennials to take care of.

4.     Check fire extinguishers in tractors and combines and trucks that will be in wheat fields.

5.     Fertilize forage fields where second cut is off.

6.     Put signs/stakes on all on-farm-plots.

7.     Install Western Bean Cutworm traps.

8.     Order and pick up your cover crop seed

Q I have saturated soils in my corn fields. How much nitrogen have I lost since the soils were saturated for about 7 days?

Ans It is very hard to tell. You may have lost up to 50% of your N because the soil was saturated for 7 days. No way to tell. N that is in the organic fraction will still be there. A more direct question is how much more should I add. I would add another 50 lbs actual N to soils saturated for 7 days. It is amazing how much corn you can grow with 50 lbs of N.

Q Did growth regulators make a difference this year to prevent wheat from lodging?

Ans It sure looks like they made a difference. Plots around the area of sprayed vs. non sprayed are showing there is less lodging where a PGR was used. But also, there is a big difference between varieties. As you drive around and see fields with two varieties one is lodged and the other is not. But we won’t know the real answer until the combines hit the fields. In the 2018 Ontario Cereal Trials there are ratings for lodging. In those trials Pro 81 is rated as having a low score for lodging. (Stands well) In those trials they did not use a high rate of nitrogen.

Picture 1 - Moddus on C&M Pro 81

Q The price of phosphorous fertilizer has really gone up. I was planning on putting some phosphorous on after second cut. How critical is phosphorous after second cut?

Ans Phosphorous is critical for forage production. If you have already applied 40-50 lbs of actual P either as fertilizer or manure you could reduce or omit P in this application. But you still should apply potassium and one pound per acre of Boron if you have not already applied boron. You should not expect a response from sulphur applied now.

Q Can I safely apply liquid manure to my new alfalfa that I seeded this year?

Ans You might have been able to before the rains. But if you have rains and manure equipment will leave ruts. I would not apply manure to these new seedings.

Economics of applying fungicides to soybeans

Passed along by BASF. I believe their results are like the other main soybean white mould fungicides as we outlined in last week’s Cropwalker, when you need to control for white mould. Approximately 2 bu/ac in low disease pressure environments, and 6 bu/ac in high disease pressure environments, average is around 3 bu/ac.

I personally have seen up to 20 bu/ac yield response to applying a fungicide due to white mould in soybeans. One of those trials was during the registration process for Cotegra.

Main foliar disease robbers in Corn – What diseases to target?

Frequently around this time of year, the question is what product should I use at tasseling? The question back is, what yield robbing diseases are you targeting? Luckily, the Crop Protection Network has a database on the main yield robbing diseases in corn. See the table below. However, you also need to consider total revenue, as discounts due to high DON levels is not accounted for.

Figure 1 - Yield Losses in Corn due to Leaf Diseases

Main foliar disease robbers in Soybeans – What diseases to target?

Like the corn question above, target the main yield robbing diseases. For root rots and stem diseases like sudden death and soybean cyst, make note for future years, so that variety selection and/or the seed treatment can be adjusted. In Ontario, the largest yield robber that can be controlled in-season is white mould. The next biggest one is Pod and Stem blight. Make sure, at a minimum, the product you are using is controlling white mould.

Figure 2 - Yield losses caused by diseases in Soybeans

I need a soybean reproductive staging guide. Do you have a good example or source?

You are out in the field and need to double check what the difference is between R1 (first flower) or R2 (full flower), or perhaps, what R3 or R4 mean when it comes to developing pods. The two listed below is a couple of the best I have found. Have something better? Please share.

K-State One Pager


Cool Beans – In-depth


The Weed Control Triangle

I made this diagram a few years ago when I was running into a few situations where weed control was less than optimal.

For starters you can only pick two sides. This leaves one side of the triangle open to be less than optimal.

Figure 3 - Weed Control Triangle

If you pick cut-rate herbicide, the weeds better be small and the weather conditions at the time of application just about perfect.

On the upper end of the herbicide label for weed size? Or hardened off due to dry weather conditions? You better be using full rate herbicide and applying in good weather conditions.

Struggling, or having to applying in less-than-optimal conditions. Weeds better be on the smaller size for the label, and don’t skimp on your herbicide rate.

Hopefully this triangle provides a few ideas if you are wondering what happened if weed control has gone sideways for you.

Ragweed Control - > triangle example below, one was beyond the leaf stage, one was applied on label. But it was applied in less-than-optimal conditions. Same field.

Picture 2 - Reflex applied in less than optimal conditions

Corn Staging

If you are out counting leaves, I would expect the first 2-3, maybe even 4 leaves in some situations, are no longer green and growing (especially in areas that had frost). You need to assume these are present when estimated plant stage.

Picture 3 - Don't forget to count corn leaves that are no longer visible

Soybean Cyst Nematode (SCN)

For some areas, SCN is old hat. In other areas with less history of having soybeans in the rotation, it is relatively new as an issue. You may start to see some of the symptoms of SCN, or notice small cysts on the roots that are not nodules. It is best to sample these areas to obtain a SCN count, which can then help with proper management of this pest. If your soybean yields have been staying stagnant, or declining, and you have properly managed your fertility and weed control. It maybe time to start sampling for SCN and putting a management plan together for this pest.

Defoliation Thresholds

Are a helpful tool for dealing with pests that are tough to determine how many the are in a field, but you can see their presence, and gauging economic impact is better done through defoliation estimations. It does take a trained eye to figure this out. One way of doing this is to use the Crop Protection Network defoliation quiz.

Disease Severity and Defoliation Training | Crop Scouting Training (cropprotectionnetwork.org)

Do NOT apply permit to Soybeans

Permit is used to take out volunteer soybeans in some classes of edible beans.

Aphids in Spring Cereals

Threshold is 10 aphids per stem, or 50 per stem at heading. One reason to control is that can act as vector for barley yellow dwarf, see below. When scouting for aphids, check over the whole plant. Last week we were finding them at the base of the plant at the soil line. This week in the same field they have moved up the stem.

Barley Yellow Dwarf in Oats

To manage barley yellow dwarf in Oats, you may need to use a neonic seed treatment to take out the first generation of aphids to prevent feeding from occurring and ending up with Barley Yellow Dwarf (aphids are a host and spread it). Yield losses in Oats can be up to 40%. See picture below for signs you may have Barley Yellow Dwarf.

Picture 4 - Plants with appearance like this had higher aphid counts.
Picture 5 - Tell tale sign is the leaf tips starting to turn a reddish colour
Picture 6 - Leaf blades at base of plant turning red
Picture 7 - Red leaf blades

Nodulation in Soybeans

Nodules close to the stem suggest inoculation from seed treatment, nodulation on the fine root hairs may suggest nodulation from native populations in the soil.

Picture 8 - Soybean nodulation concentrated close to the main stem
Picture 9 - Nodulation close to the main stem, with additional nodulation on laterals.

Nightshade or Pigweed?

Somewhat similar leaf shape, but nightshade has a point, pigweed has what looks like a pig’s butt on the end of the leaf blade.

Picture 10 - Pigweed with "pig's butt" at leaf tip
Picture 11 - Nightshade with pointed leaf tip

Planted soybeans 3” deep?

Seemed to come out of the soil fine. See below. As a rule of thumb, I would not plant this deep unless you were trying to reach soil moisture for germination. This grower is glad that they did on this field. Final population is about 135,000 after dropping 170,000 seeds.

Picture 12 - Soybeans emerged with 3" planting depth

Is my volunteer Corn dead?

To check to see if the volunteer corn has succumbed to Assure II (quizalofop-p-butyl), pull the centre of the plant out from the whorl. If the growing point has turned brown, the plant is dead.

Picture 13 - Leaf discoloration with corn whorl tip discolored
Picture 14 - Corn whorl has turned brown.

Can I use tissue sampling to figure out my corn nitrogen requirements?

NO! It is a useful tool for crop diagnostics, but it cannot determine how much nitrogen is available in the soil for the crop, just that it may or may not be limiting at that growth stage. Unless you are peak growth stage for nitrogen uptake, you will not be able to use tissue sampling to determine in-crop nitrogen rates.

Soybean Aphid, Bean leaf beetle, and Spider Mite training materials

A few materials I have come across for the identification, lifecycle and thresholds of these pests.

Aphids - https://extension.entm.purdue.edu/fieldcropsipm/insects/soybean-aphid.php

Bean Leaf Beetle - https://extension.entm.purdue.edu/fieldcropsipm/insects/bean-leaf-beetle.php

Grasshoppers - https://extension.entm.purdue.edu/fieldcropsipm/insects/soybean-grasshopper.php

Spider Mites - https://fieldcropnews.com/2016/08/two-spotted-spider-mites-in-edible-beans-and-soybeans/

Cover Crop Blends…

If you are planning on growing a cover crop following wheat, suggest you get these lined up sooner than later, if you have not done so already.

A few of my favourites

1)    Oats – winter kills, different disease spectrum than other crops, suppresses weeds, easy to control. Makes good forage feed. Harvest at late boot stage

2)    Cereal Rye – does well without much regard to seeding date, lots of early season growth for weed suppression. Allelopathy can be good or bad for weed control/crop establishment.

3)    Winter wheat – easy to kill, it is cheap, usually already on the farm, no issues with allelopathy.

4)    Barley – will make feed without needing a fungicide for crown rust, like you need in Oats. Forage yield is less than oats.

5)    Purple top turnip – great nitrogen sink, with slow decomposition in the spring. (Less nitrogen losses than say, tillage radish/daikon radish)

6)    Austrian Winter Pea – will grow in cool conditions, but rarely survive the winter (in my experience)

7)    Triticale is compared to cereal rye. It over winters well and will make more forage next spring than cereal rye.

May add a few more in the next issue, when back from our summer break.

“Strike while the iron is hot.”

— John Deere